Plate Tectonics Defenitions Flashcards
(24 cards)
Composite Volcano
This is a large cone shaped volcano made up of alternate layers of acidic lava (gentle eruptions) and ash (violent eruptions)
Fold Mountains
Fold mountains are mountain ranges that are formed when two of the tectonic plates that make up the earth’s crust push together at their border. The extreme pressure forces the edges of the plates upwards into a series of folds
Hotspot Volcano
These are volcanoes that are not associated to plate boundaries, they are found in the middle of plates
Caldera Volcano
A cauldron-like shaped volcano which forms when the build up of gases becomes too extreme causing explosions which clear the magma chamber beneath the volcano. This causes the summit to collapse back into the chamber, forming a crater.
Shield volcano
A broad domed volcano with gently sloping sides formed by numerous balsatic lava flows
Collision boundary (two continental)
If two continental land masses meet, the two will crush together, crumbling and folding upwards, resulting in fold mountain ranges
Conservative plate boundary
These are two plate boundaries which slide past each other, sometimes catching on each other and building up immense pressure which eventually releases in an earthquake
Earthquake
The movement of the ground caused by tectonic plate activity. This is either movement of the plate boundary, fault zones caused by tension or compression which makes the plate rip or expansion of magma chambers in volcanoes
Destructive Plate Boundary
A plate boundary which occurs when an oceanic crust is forced into a less dense continental crust, causing the oceanic crust to sink under the continental crust as it is denser.
Continental Drift
The gradual movement of the continents across the earth’s surface over time due to convection currents in the mantle.
Conservative Plate Boundary
This is where two plates have lateral movement, so they move past each other. The plates either move in opposite directions or in the same direction at different speeds. Due to the friction, the plates often get stuck, building up immense pressure, which is eventually released, causing an earthquake.
Pyroclastic Flow
Dense mixtures of hot, dry rock fragments and hot gases which move away from the vent that erupted them at high speeds. It flows at roughly 50-60km/ph
Magma
This is the molten rock which lies below the earth,s crust. When ejected, it is called lava
Subduction
The process which takes place at a Destructive Plate Boundary when one tectonic plate moves under another and sinks into the mantle as the plates converge, forming a subduction zone
Active Volcano
A volcano that has had at least one eruption in the past 10,000 years
Dormant Volcano
A dormant volcano is an active volcano that isn’t erupting, but will supposedly erupt again
Main Shock
The most powerful earthquake, lasting as little as 10 seconds to as long 5 minutes
Aftershock
A smaller earthquake following the main shock, caused by resettling. There can be hundreds of aftershocks and can carry on up to 6 months after the main shock
Secondary waves
These are waves which travel 17 times slower than P-waves and can only travel through solids
Long waves
There are two types:
- rayleigh waves = extremely violent rolling motion moving 15 metres/second
- Love waves = snake motion
Primary waves
These are the fastest earthquake waves and are able to travel through liquids and solids. Also known as P-waves
Epicentre
The point on the earth’s surface vertically above the focus of the earthquake
Focus
The point of origin of an earthquake
Fissure
A large, narrow opening made by cracking or splitting in the rock
